Chang Fei-Fan, Zhang Lei, Zhao Pei-Chen, Huang Wei
State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructures, School of Chemistry and Chemical Engineering, Nanjing University , Nanjing 210093, People's Republic of China.
Inorg Chem. 2018 Feb 5;57(3):1438-1448. doi: 10.1021/acs.inorgchem.7b02835. Epub 2018 Jan 11.
Three 46-membered [2 + 2] pendant-armed Schiff-base macrocyclic dinuclear Cd and Cu complexes (2a, 2b, and 3b) and one 23-membered [1 + 1] Cu macrocycle 4a were prepared from the template-directed condensation reactions between 1,2-bis(2-aminoethoxy)-ethane and extended Cl-dialdehyde in the presence of CdX and CuX (X = Cl and Br), in which halide effects play important roles in the organization of final macrocyclic complexes in addition to the dominant influence of metal cations. Transmetalation was intensively studied among these Cd and Cu complexes with large and flexible macrocyclic ligands, including two previously synthesized dinuclear Zn macrocycles (1a and 1b). Our results indicate that Zn → Cu and Cd → Cu transmetalation proceeds more quickly than that from Cd to Zn, and all the processes are found to be irreversible. It is noted that a [2 + 2] heterodinuclear CdZn macrocyclic intermediate could be detected by ESI-MS together with [2 + 2] homodinuclear Cd and Zn macrocyclic complexes. Furthermore, distinct halide behavior was observed in the in situ Cd → Cu and Zn → Cu metal-ion exchange. That is to say, [2 + 2] macrocycles (1a and 2a) could be converted to [1 + 1] macrocycles 4a and 4b under the reflux condition in the case of CuCl, accompanied by the configurational transformation from half-folded dinuclear Zn and Cd to unfolded Cu macrocyclic skeleton. In contrast, CuBr leads to a highly efficient transmetalation to corresponding [2 + 2] dinuclear Cu complex 3b from both 1b and 2b no matter the experimental condition used.
通过1,2 - 双(2 - 氨基乙氧基) - 乙烷与扩展的氯代二醛在CdX和CuX（X = Cl和Br）存在下的模板导向缩合反应，制备了三种含46个原子的[2 + 2] 悬挂臂席夫碱大环双核镉和铜配合物（2a、2b和3b）以及一种含23个原子的[1 + 1] 铜大环配合物4a。在这些配合物的形成过程中，除了金属阳离子的主要影响外，卤化物效应在最终大环配合物的组装中也起着重要作用。对这些具有大且灵活大环配体的镉和铜配合物之间的金属转移反应进行了深入研究，其中包括两种先前合成的双核锌大环配合物（1a和1b）。我们的结果表明，锌到铜和镉到铜的金属转移比镉到锌的金属转移进行得更快，并且发现所有过程都是不可逆的。值得注意的是，通过电喷雾电离质谱（ESI - MS）可以检测到[2 + 2] 异双核镉锌大环中间体以及[2 + 2] 同双核镉和锌大环配合物。此外，在原位镉到铜和锌到铜的金属离子交换中观察到了明显的卤化物行为。也就是说，在氯化铜存在下回流条件下，[2 + 2] 大环配合物（1a和2a）可以转化为[1 + 1] 大环配合物4a和4b，同时伴随着构型从半折叠的双核锌和镉转变为展开的铜大环骨架。相比之下，无论使用何种实验条件，溴化铜都能导致1b和2b高效地金属转移为相应的[2 + 2] 双核铜配合物3b。
